Model Sawmill Dreaming---

[bret4]

This video shows stops that are being used to get the board size. It also shows how the blade is tensioned on this saw at the top with adjustable screws. Much the same way a hacksaw blade is tensioned.

[ame]http://youtu.be/CcbeAFpt6bU[/ame]

 

[Brian Rupnow]

Good Grief, its been a long afternoon in my little shop. My bandsaw blade is dull, and I had to cut close to 60" of 3/4" aluminum to make the two outer frame towers shown here. Then after they were sawed out, I milled all the sawcuts----which is quite fine, considering that the towers are 13" tall, and the maximum table movement on my milll is 11 1/2". However, there was nothing else very exciting going on in my life, and my wife was busy doing things in her office upstairs. I have learned #1--Not to drag things up to show her for approval. All shop artifacts look the same to her. #2---If I am going to do something real stinky (as in burning cutting oil) to open the window in my little shop even if its 40 below zero, so the smells don't make it upstairs to where she is working. I expect that tomorrow I may actually finish these two towers. If so, I will have to go downtown before noon and buy a peice of 6 x 3/4" aluminum plate x 18" long for a baseplate to mount them to. I called a custom trim and molding company today, and they do sell finished 3/4" square oak for 54 cents a foot, so that is probably what I will build my carriage from.

 

[Brian Rupnow]

For some reason, I can't get sound on these youtube videos. My speakers are turned on, nothing is muted, but I'm not getting sound. Anybody got a suggestion?

 

[johnmcc69]

All I hear is: Brian!! KEEP IT DOWN! STOP MAKING SO MUCH NOISE!!
FEED THE GARBAGE..TAKE OUT THE CAT!! I MEAN..FEED THE CAT..

& finally, "YES DEAR.".

 

[Brian Rupnow]

johnmcc69---My wife is one of those super women that I was fortunate enough to find 25 years ago. (I had 15 years with the OTHER kind of woman, so I know what I am talking about). My wife is a professional in the human resource and career path counseling field. We both work from home offices, and yes, it can get a little crazy around here by times. She professes to know (or want to know) very little about the world of engineering and fabrication and machining. I know even less about human resources and career path counseling.---And yet, somehow, we make it work very well.

 

[Brian Rupnow]

I need to know something. I have read a number of conflicting opinions related to carriage advance and sawstroke timing. My plan all along has been to have the carriage advance while the saw is moving down in its cutting stroke, and to "pause" while the saw is moving up on its non cutting stroke. Last night I read the exact opposite on a website. This isn't a big problem for me to change, as the eccentric wheel is only attached to the main "crankshaft" with a setscrew and can easily be rotated 180 degrees out of phase. On another website, I read that the two main columns which the saw frame slides up and down in are tilted in the direction of carriage travel towards the sawblade at the top, by a number of degrees. The theory here is that as the saw is travelling up on the non cutting stroke, the angle of the support columns/guides causes the log to move away from the cut, and that the carriage advances during this upward travel of the saw. Then when the saw travels down on its cutting stroke, the carriage pauses and the saw cuts into the log on its downstroke due to the angle of the support columns.----This is something which I can not easily change "after the fact", without tilting the main columns and having things look a bit goofy. (If I was going to use this last approach, I would leave the columns vertical and cut the internal guide slot on an angle). Any advice would be greatly appreciated, as I hope to finish those columns today.----Brian

 

[johnmcc69]

Brian, I apologize for that, I didn't intend for that
To sound like I was judging anything. It just sounded
Funny at the time. I'm sorry.

John

 

[Brian Rupnow]

Brian, I apologize for that, I didn't intend for that
To sound like I was judging anything. It just sounded
Funny at the time. I'm sorry.

John

John---Don't be sorry----It was funny!!!

 

[f350ca]

Brian,
Advancing the carriage on the non cutting stroke would leave the blade loaded as it tried to move on the cutting stoke. I'd expect the blade would wonder under those conditions.
With the eccentric advancing the log, as you have it, the blade starts down under no load, the eccentric accelerates the log forward to the middle of the stroke then decelerates for the remainder giving the teeth time to remove the cuttings.
Angling the blade changes the cutting action to a point. At the extreme if the blade was parallel to the log you'd be ripping the fibres and get log stringy cuttings, rather than shearing them.
I tried ripping cedar blocks with a bandsaw blade to make shingles, the cuttings were unmanageable and the added surface in contact with the blade made it slower to advance. I settled with conventional cross cutting and poorer surface finish.

 

[Brian Rupnow]

Someone just told me that its "Ratchet and Pawl"----Not "Ratchet and Paul'".---My apologies to all the Pauls out there!!! Damn, I knew that too.

 

[bret4]

I may be wrong, but in the videos I posted it looks like it is advancing as the blade on the up stroke. On an old machine made of wood there may be enough give in all the moving parts that this would work fine.

Then I have to wonder if the aggressive blade they are using tends to pull itself into the log on the down stroke cutting so deep that they needed to time the advance on the up stroke so the blade would give them a full cut on the next down stroke.

Anyway you look at it I think it would be a good idea to be able to adjust when the advance happens because a small precisely made model may not react the same as the real thing.

 

[Brian Rupnow]

The slots in these outer frame columns are 5/8" wide x 3/8" deep x 10 5/16" long. When you don't have any power feeds on your mill, Damn, thats a lot of cranking. I can only take a .030" depth of cut or the mill doesn't like it much.

 

[starnovice]

"...Damn, thats a lot of cranking..."

I know what you mean Brian. I don't have power feed either because I thought they were too expensive. I am starting to re-think that. At least it builds up your biceps, or in the case of arthritis it builds up your pain threshold level.

Pat

 

[Cliff]

Hey Brian
As usual your work is top notch. You was saying that your Mill doesn't have a power feed why don't you build one here a while back I read a post where Ozzie 46 built one so why don't you. Always following a long. Cliff

 

[Brian Rupnow]

Cliff---Thanks for following. I really don't want a power feed. It is very rare for me to mill things this large/long. It would just be one more thing to worry about crashing.----Brian

 

[aonemarine]

spring load carriage to the blade???

 

[Brian Rupnow]

 

[Brian Rupnow]

spring load carriage to the blade???

What are you talking about??

 

[aonemarine]

Yea im terrible at explaining things... put springs on the carriage that holds the log to keep pressure against the blade and then not let the carriage advance until the log is sawn thru to remove the pressure then allow the carriage to advance. I was thinking this until i saw where you wernt looking for a power feed on the carriage.

 

[Brian Rupnow]

aonemarine---Go back and read the whole thread. There is a power feed on the carriage. Thats what the ratchet and paul and rack and pinion are about. I do NOT have a power return on the carriage. Although it is possible to have a power return, as shown in one of the videos I linked to, I don't think I am going to bother with one.